T Characteristics and genetic analysis of multi-fault,multi-convex and multi-depression structure in Dongpu Sag
Starting from the Bohai Bay Basin,the structural characteristics of Dongpu Depression are stud-ied,and the structural analysis of Dongpu depression is carried out with the data of seismic section,drilling and logging.The results show that:1)Dongpu Sag has the characteristics of multi-stress superposition space-time evolution of the Indosinian compressional north-south zone,the Yanshanian weak compres-sional,the Paleogene Sha4-Sha3 strong tensile east-west zone,and the late Paleogene strong strike-slip weak tensile fault block.It presents a tectonic pattern of alternating upturns in plane,upturns in verti-cal depressions and checkerboard interleaving faults.2)Dongpu Sag has undergone four stages of structural evolution and developed a thrust-extension-strike-slip fault system.According to the superposition char-acteristics of tectonic deformation stress,the Middle Paleozoic tectonic styles in Dongpu Sag can be divided into two categories and nine types,and the Paleogene tectonic styles can be divided into anticlinal,fault stage and back type,and a total of 14 types.3)Right-lateral strike-slip displacement of mantle overarc-hing and deep faults caused by plate tectonic activities is the fundamental dynamic cause of Cenozoic forma-tion in Dongpu Sag.The existence of the Paleogene basement lateral structure,the difference of the activity stages of the Lanliao fault and the development of a large number of depression-controlling faults,and the transition from single depression to multi-fault,multi-convex and multi-depression.A large number of grade 4 and 5 faults developed in the late Paleogene shallow layer adjusted the depression and bulge,gradu-ally strengthened the strike-slip tectonic stress,and the distribution pattern of faults in the plane changed from lateral row to column row,resulting in the twisting tectonic deformation of the multi-fault,multi-convex and multi-depression pattern,the early formed oil and gas reservoirs have been adjusted and trans-formed,which provided a good theoretical support for the fine exploration and development of Dongpu Sag.
Dongpu Sagtectonic stresstectonic styletectonic evolutionfracture system
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